Week 3 Flashcards
Microevolution
Small genetic changes in a population over time
Species
A group of organisms that can interbreed and produce fertile offspring
Speciation
The process by which one species splits into two or more new species
3 phases of speciation
- Separation
- Divergence
- Reproductive isolation
Phase 1 of speciation, separation
A species splits into groups due to physical or environmental barriers
Allopathic Speciation
Populations are separated by some physical barrier
Sympatric Speciation
Speciation that happens without physical separation, often due to genetic changes or behavioural differences
2 mechanisms of separation for allopatric speciation
- Long-distance dispersal
- Vicariance
Long-distance dispersal, allopatric speciation
When a small group migrates far from the main population and evolves separately
Vicariance, allopatric speciation
When a physical barrier splits a population, leading to separate evolution
Phase 2 of speciation, divergence
The separated groups evolve differently due to natural selection or genetic drift
Reproductive isolation
- When two populations have changed so much they can no longer interbreed
- Marks the end of speciation
Local host race formation
When a population adapts to a specific host or habitat, leading to genetic differences over time
Phase 3 of speciation, reproductive isolation
The groups become so different that they can no longer interbreed, forming new species
Speciation by polyploidy
When a new species forms due to having extra sets of chromosomes, common in plants
Hybridization
When two different species mate and produce offspring (hybrids)
3 outcomes of hybridization
- Fusion
- Stability
- Reinforcement
Hybrid Zones
Regions where hybridization occurs and can be studied
What is a stable hybrid zone?
A hybrid zone where hybrids continue to form over time without one species outcompeting the other
Genetic homogenization
When gene flow reduces genetic differences between populations, making them more similar
Reinforcement
When natural selection strengthens reproductive barriers to prevent hybridization
Origin of life
Transitioned from inorganic to organic molecules
Progenote
- First living organism
- Had DNA and amino acids
What did eukaryotes arise from?
A mutated archaea
How did multicellular organisms arise?
- Single-celled organisms grouped together for survival
- Over time, some cells specialized, leading to true multicellularity
Order of evolution for eukaryotes
protists —> fungi and animals
Colonization of Land
When plants, animals, and fungi moved from water to land and adapted to live there
Fossil record
Provides historical snapshots but can be inaccurate
How are isotopes used in fossils?
Radioactive isotopes help determine a fossil’s age through radiometric dating
Mass extinction events
five major events that shaped current species
Adaptive Radiation
- When one species evolves into many new species to fill different roles in an environment
- Occurs after mass extinction
Paedmorphosis
When an organism retains juvenile features into adulthood
Regulatory genes
Genes that control the expression of other genes, guiding development and cellular functions
Macroevolution
Large-scale evolutionary changes that occur across species
Phylogeny
the study of how species are related through evolution
Taxonomy
Classification system for organisms
Genealogy
The study of family history and the descent of individuals or groups
Monophyletic group
Groups that include a common ancestor and all its descendants
Paraphyletic group
A group that includes a common ancestor but not all of its descendants
Polyphyletic group
Lacks the most recent common ancestor
Homologous traits
Traits shared by species due to a common ancestor
Analogous traits
Traits that appear similar in different species but evolved independently, not from a common ancestor
Outgroups
- A species or group that’s related but not part of the ingroup
- used for comparison
Ingroups
- The group of species being studied
- Compared to outgroup
Molecular clock
Predicts evolutionary timing using mutation rates
Anisogamy
Reproduction with different-sized gametes
What are the 2 main factors that drive sex differences?
- Offspring energy and care requirements
- Mating system
Intrasexual selection
Competition between males for access to females
Intersexual selection
When females chooses mates based on traits, ‘charm’
Female Passivity
The idea that females are less active in mating choices
Bateman’s Principles
- Males have higher variance in the number of mates than females do
- Quality of mate is most important for females, not quantity
- Male reproductive success is more closely linked to the number of mates
Implications of Bateman’s Principles: Males
Males face more competition for mates, leading to traits that help them attract partners
Implications of Bateman’s Principles: Females
- Energy is the limiting resource for achieving Darwinian fitness
- Females should be choosier about who they share their gametes with
Misdirections of Batman
- Stereotypes limit the exploration of diversity
- Implies that sperm are cheap and mating is without risk
- Implies that females increase reproductive success only by choosing better mates, not by mating more
